A HVAC system, for example a chiller with shell and tube heat exchangers, sometimes uses a centrifugal compressor. The centrifugal compressor generally includes a motor configured to drive one or more impellers, and the compressor may be housed in a compressor casing. During operation, refrigerant can be sucked into the compressor casing and compressed by a centrifugal force, thus creating a relatively high pressure inside the compressor casing. In some situations, the compressor casing may be configured to include two separate covers that are jointed together by a mounting mechanism, such as bolts and nuts so that the compressor casing can be opened, for example for service purposes.